[wdmaudiodev] Positive/negative dB range in volume control

  • From: Eugene Muzychenko <eugene@xxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 8 Jul 2011 21:38:16 +0700


Found a strange behavior of Windows volume level regulators. If a
driver returns a volume level range that crosses the zero
(-n..+n dB), Windows volume control applets (XP and Win7) make a
very uneven scale for the sliders. For example, if the range returned
is -90..+90 dB, the "0 dB" position is about 5% from the bottom
(almost a lower position). If the range is -90..+60 dB, the zero
position is a little higher (about 7%). Only with a very narrow positive
range (-90..+12 dB), the zero position is near to the center.

It looks like a "logarithm of a logarithm", i.e. a slider scale is
double-logarithmic, while it should be linear for the dB levels.

Why volume control application do such strange scaling? Maybe there is
a way to make a linear slider scale?



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